1. Field of the Invention
This invention relates generally to electrosurgery and more specifically to the efficient control of electrosurgical cutting coagulation cautery and fulguration.
2. Discussion of Related Art
The mechanism of electrosurgery is well known in its capability to perform exacting surgical cuts and to provide coagulation, cautery, fulgration and other unique effects. In general, electrosurgery involves the discharge of high voltage at a very high frequency, typically in the form of a spark or arc. However, as with any electrical spark discharge, control is always an issue. Without oversimplifying environment effects, it generally is well known that electricity tends to follow the course of least resistance. Unfortunately this tendency works against the need of a surgeon to have absolute control of an electrosurgical discharge, for example when he is attempting to make a precise surgical incision in very tight quarters, as is the case in laparoscopic procedures.
Failure to achieve this control can cause inadvertent discharge of the electrosurgical spark to an undesirable location. For example, if a metal grasper or clamp is holding a portion of tissue, the electrical spark may discharge to the grasper or clamp rather than overcome a smaller gap to the target tissue. This inadvertent discharge is even more probable realizing that a small gap between target tissue and the electrode is important to achieve an optimal electrosurgical effect.
The designers of electrosurgical generators have produced complex high frequency wave forms and blends of such wave forms, as well as sophisticated feedback and patient monitoring systems to achieve the present level of safety and efficacy. However, there is always the potential for accidental discharge and ancillary damage, particularly when electricity is provided in an open environment. In comparison, to electrical current flows in a wire, electrosurgical discharge by way of an arc has not been particularly controllable. Certainly, a device and method adapted to control and direct an arc of electrosurgical energy would be particularly beneficial.
It is appreciated in U.S. Pat. No. 5,509,916, that a laser can be used to establish an ionized conductive pathway for electrosurgery. The laser ionizes the molecules of air along the laser beam, thereby establishing a path of least resistance leading to an operative site. An electrosurgical spark or arc will follow this path of least resistance, ultimately producing an electrosurgical effect at the operative site. Thus, the laser effectively establishes a means for controlling the electrosurgical arc, thereby avoiding an inadvertent or misdirected discharge.
While this system may work well in air, such a gas may neither be available nor desired in an electrosurgical environment. For example, lasing air would not be available in a laparoscopic environment if carbon dioxide were used as an insufflation gas. Furthermore, complete ionization of (rather than mere excitation) environmental air by a laser may not maximize the efficiency of the laser in establishing a pathway of least resistance.
In accordance with the present invention, a device and method is disclosed for initiating, directing, and maintaining an electrosurgical discharge in a highly controlled manner. A virtual wire is created which substantially avoids inadvertent and misplaced discharge of the electrosurgical energy. In one aspect, the present invention provides for an environment of gas molecules to be merely excited by a low-power laser beam to create a well-defined path to a precise target. An electrosurgical generator is then provided with sufficient power to fully ionize the excited molecules, thereby creating a path of least resistance to the operative site.
In a preferred embodiment, the device may use the ambient gas of a laparoscopic environment, namely carbon dioxide, and a low powered laser to direct and control an electrosurgical instrument discharge. In an alternate embodiment, the electrosurgical instrument may supply the environmental gas as well as the laser beam. The gas stream and/or the laser beam may be scanned, pulsed, defocused, or otherwise varied to provide a variety of electrosurgical effects.
In order to maximize the efficiency of the system, the laser can be provided with power only sufficient to energize the atoms of the environmental gas. Once these energized atoms have established the pathway to the operative site, energy from the electrosurgical generator can be used to fully ionize the excited molecules to define the path of least resistance.
The present invention can also be used in an environment where air is neither available nor desired. For example in laparoscopic surgery, the insufflation gas, such as carbon dioxide, can provide the environmental gas and can be lased to define the pathway.
Further efficiencies can be generated by providing a laser beam at a frequency depended upon the excitation frequency of the environmental gas. Thus, a carbon dioxide gas discharge laser can most efficiently be used to excite carbon dioxide molecules, for example, in a laparoscopic electrosurgical procedure.
In one aspect, the invention includes an electrosurgical apparatus which is adapted to perform electrosurgery at an operative site on a patient. The apparatus includes a source of shielding gas that provides gas molecules having properties for being energized at a particular frequency to an excited state. A first delivery apparatus is coupled to this source of gas and adapted to deliver the gas molecules in the proximity with the operative site. A laser is adapted to produce a laser beam providing laser energy at a frequency equal to about an integer multiple of the particular frequency of the environmental gas, and at a power generally sufficient to excite the gas molecules. A second delivery apparatus is coupled to the lasers to deliver the laser beam along a pathway leading toward the operative site. An electrosurgery generator provides electrosurgical power and is coupled by a third delivery apparatus which delivers the electrosurgical power along the pathway toward the operative site. A handpiece including a housing and an elongate probe can be used for one or all of the first, second, and third delivery apparatus. The laser energy is provided in an amount generally insufficient to ionize the gas molecules along the pathway. However, the electrosurgical power is provided in an amount generally sufficient to ionize the gas molecules excited by the laser.
In another aspect of the invention, an electrosurgical method is used to perform electrosurgery at an operative site of a patient. The method includes the step of providing a source of environmental gas molecules having an excitation frequency. These molecules are moved into proximity with the operative site and energized with a laser beam having a frequency equal to about an integer multiple of the excitation frequency of the environmental gas. The laser beam is controlled to provide power sufficient to excite the gas molecules along a pathway leading toward the operative site. Electrosurgical power is delivered along this pathway to the operative site to perform the electrosurgery on the patient. The pathway can be established by one or more and the electrosurgical power can be provided in either a monopolar or bipolar configuration.
In another aspect, the invention includes a laparoscopic method for performing electrosurgery at an operative site in the abdomen of a patient. This method includes the step of insufflating the abdomen with gas molecules having an excitation frequency, exciting the gas molecules with a laser beam having a fundamental frequency or a harmonic thereof equal to about the excitation frequency of the insufflation gas, and delivering electrosurgical energy along the pathway of excited molecules to perform the electrosurgical operation at the operative site. The laser beam can be moved relative to the patient to vary the size and shape of the pathway. Either or both the laser beam and the electrosurgery energy can be pulsed.
In a further aspect of the invention, an electrosurgical method is used to perform laparoscopic electrosurgery at an operative site in the abdominal cavity of a patient. The cavity is initially insufflated with a gas having an excitation frequency. This insufflation gas is then lased at a lasing frequency to form a pathway of excited gas molecules leading toward the operative site. Electrosurgical energy is directed along this pathway to produce an electrosurgical effect on the patient.
In another aspect of the invention, a catheter having a proximal end and a distal end is adapted to perform electrosurgery within a body conduit. The catheter includes an elongate shaft which delivers an environmental gas into the conduit. A laser apparatus includes a light fiber carried by the shaft and adapted to release laser energy into the environmental gas to excite gas molecules along the pathway. An electrosurgical apparatus includes an electrode carried by the shaft and adapted to release electrosurgical energy along the pathway to perform electrosurgery along the body conduit. A balloon can be carried by the shaft and inflated with a gas which is controllably released through a hole in the wall of the balloon. This release provides the environmental gas which is lased to produce the pathway. An associated process includes the steps of inflating the balloon with an inflation gas, releasing a portion of the inflation gas from the balloon, exciting molecules of the inflation gas with laser energy to produce a pathway, and introducing electrosurgical energy into the pathway to perform electrosurgery within the body conduit.
In still a further aspect of the invention, the laser which is used for exciting the gas molecules provides a laser beam which is generated from an active medium having a discharge frequency. The active medium may be a gas or a crystal and may be tunable to vary the discharge frequency.
These and other features and advantages of the present invention will become more apparent with a description of preferred embodiments and reference to the associated drawings.